Electrical coupling between elements in relative motion in respect of each other

ABSTRACT

The electrical coupling of two components A and B, which execute a relative motion to one another, is achieved by means of one or more curved conductive blades operating below their elastic limit, and guided along surfaces over which they roll without slip, with a substantially constant radius of curvature; the blades are inserted at their ends to the conductive portions of said surfaces.

United States Patent [191 Brenot et al.

ELECTRICAL COUPLING BETWEEN ELEMENTS IN RELATIVE MOTION IN RESPECT OFEACH OTHER Inventors: Claude Brenot; Gaston Mollard, both of Paris,France Assignee: Thomson-CSF, Paris, France Filed: July 12, 1973 Appl.No.: 378,628

Related US. Application Data Continuation of Ser. No. 180,003, Sept. 13,1971, abandoned.

US. Cl. 191/12 R, 339/5 R Int. Cl H02g 11/00 Field of Search 191/12 R;339/6 R, 6 A,

References Cited UNITED STATES PATENTS 11/1968 Ober 191/12 R Nov. 19,1974 3,505,544 4/1970 Helms ..3l0/13 3,599,165 8/1971 Wendell ..339/5Primary Examiner-Robert S. Ward, Jr. Assistant Examiner-D. W. KeenAttorney, Agent, or Firm-Edwin E. Greigg [57] ABSTRACT The electricalcoupling of two components A and B, which execute a relative motion toone another, is achieved by means of one or more curved conductiveblades operating below their elastic limit, and guided along surfacesover which they roll without slip, with a substantially constant radiusof curvature; the blades are inserted at their ends to the conductiveportions of said surfaces.

2 Claims, 6 Drawing Figures PATENM; nuv 1 9 I974 SHEET 2 OF 3 P'IXTIiNTEL NOV 1 91974 SHEET 3 OF 3 ELECTRICAL COUPLING BETWEEN ELEMENTSIN RELATIVE MOTION IN RESPECT OF EACH OTHER This is a continuation ofapplication Ser. No. 180,003, filed Sept 13, 1971, now abandoned.

The present invention relates to a device for the transmission ofmultiple electrical data between two elements between which there isrelative movement. In numerous devices, as for example gyroscopes,incidence detectors, electrical data have to be transmitted betweencomponents between which there is relative, generally linear or circularmotion, this without any risk of wear and poor contacting (phenomenawhich do occur in the case of sliding contacts). On the other hand, incertain instances and in particular in the context of gyroscopes, themechanical forces generated by the electrical coupling device have to bekept very small.

The device in accordance with the invention meets all theserequirements; moreover, it has the advantage over the known kind offlexible connections employed in telephone systems, that it is moreresistant to vibration; finally, it enables the transmission ofrelatively heavy currents (as much as some few amps, for example), whichis practically impossible under the same circumstances, when using wireconnections, which can only carry a few milliamps.

.According to the invention, there is provided an assembly for theelectrical coupling of two elements in relative motion, in respect ofeach other, said assembly comprising two components respectivelyintegral with said elements, said components having respective wallswith the same centre of curvature, and at least one flat conductivespring, said spring having ends respectively attached to saidcomponents, said spring being arranged to roll without slip, with asubstantially constant curvature, on said walls in the course of saidmotion, the mechanical characteristics of'the spring being such thatduring the movement the elastic limit is not reached.

For a better understanding of the invention and to show how the same maybe carried into effect, reference will be made to the drawingsaccompanying the ensuing description and in which:

' FIGS. 1 and 2 are diagrams illustrating the principle of the couplingsystem in accordance with the invention; and

FIGS. 3, 4, 5 and 6 illustrate elevational and sectional views of anembodiment of the invention.

In order to describe the principle of the invention, it will be firstassumed that each element carries only one electrical terminal and thatthis coincides with the point of attachment of the connecting device.

FIG. 1 relates to the case of elements A and Bin rectilinear relativemotion in respect of each other and FIG. 2 to the case of componentswhich have a circular relative motion about a centre for purposes ofexplanation, it will be assumed that B is fixed; the arrows F, and Findicate the direction of displacement of the component A. A leafspringR, made for example of beryllium bronze, is attached at its endsrespectively to the terminals a and b on the elements A and B, so thatduring the relative motion, the springstrip rolls on the correspondingwalls of A and B, without any sliding.

Where the elements A and B are not suitably designed;

to permit this rolling motion to take place, respective components,suitably designed, aremade integral respectively with these elements,references A and B being now used to designate the component parts onwhich the springs roll.

In the case of FIG. 1, the mutually opposite walls of A and B aretherefore retilinear, parallel to the direction of displacement. In thecase of FIG. 2, these walls are circular and concentric. The springs arefixed, for example inserted, at a and b in FIGS. 1 and 2; however, itgoes without saying that the terminals 0 and b may as well not belocated on the mutually opposite faces of A and B: in all cases, thepoints of casing must be in permanent electrical contact with theterminals. With the exception of the points of attachment, there is noelectrical contact between the springs and the components A and B,either because the springs are covered with an insulating film orbecause components A and B themselves are made of an insulatingmaterial. It goes without saying that 11 pairs of terminals such asthose a, b can be provided, which may be interconnected by anappropriate number of respective springs. In both cases, i.e., that ofrectilinear motion and that of circular motion, the radius of curvaturer of the springstrip remains constant: the elastic energy stored in thespring. remains constant in the first case, where there is no couple; inthe second case, it varies a little because of the variation of thelengths of the spring portions having respectively the radii ofcurvature R and R The radius of curvature r will be made sufficientlylarge to keep the elastic stresses low: under these conditions, thespringstrips roll on the walls A and B without slip.

FIG. 3 is an elevational view of an embodiment of the invention. In thisexample, the two components A and B are concentric and in a relativecircular motioninrespect of each other, the components comprise 12 pairsof terminals a b a b the terminals a, (i 1,2...n) being fixed to thecomponent A and the terminals b, to the component B. It is assumed thatthe relative movement between the two sets of terminalsis an alternatingmovement limited to an angle of 1- 35.

The spring blades are arranged in two axially offset groups; one of thegroups comprises-the springs R,, R R R R and R coupling the. terminalsag, b',.of odd order i,.whilst the second group comprises the springs RR R R R and R which couple the terminals of even order i; the springsofthe two groups are. in thisexample staggered in a circular sense, thusavoiding-interleaving of the connections of the two groups. of springs.

Of course, this is not an essential. feature; the springscouldiequally-well not be staggered. at all: it would merely suffice to extendthe. electrical contacts of the. points of attachment of the. springs inone:of thegroups, in order to connect them to-offset terminals. Also,and. this depends essentially upon the application desired, theterminals associated with the two groups couldibe. arranged on oppositefaces of'theflat' pieces which-here: constitute the components A and. B;

For example, the terminals (1 b, could be soldered to.

studs 0,, d, themselves soldered. to. printed circuits 011 therespective pieces A and B;

FIG. 4 diagrammatically illustrates a section in a planepassing throughthe shaft X'to whichthecompo nent Bis fixed; in order tosimplifythefigure, it will be. assumed here, that the two groups are.not angularly, offset from one another; the. drawingiis: not' to-scale:This figure simply illustrates the. axial. offset between the two groupsof leaf-springs; the attachment, connection and insulation details ofthe springs, have not been illustrated. It is assumed that the springsa, and a, 1 are fixed in the same plane of section.

In reality, because of the axial offset or stagger between the twogroups, only one spring can be seen at a time in a section taken in aplane passing through the axis; the springs of the two groups can beseen in FIG. 5, the latter being a sectional view through the device ofFIG. 3 on halfplanes defined by (10 and B respectively.

In this example, the springs of one and the same group are identicalwith each other but this of course is not a characteristic feature ofthe invention; in particular, the width of the springs will bedetermined by the current which they have to carry. The springs areguided by the faces of the casings, so that there shall be no frictionon the lateral surfaces. The odd number springs, being designed in thisexample to carry the heavier current, are wider than shown in FIGS. 5and 6 and they are also longer.

Grooves are formed in the components A and B at 1 1 and 21 for thesprings of the first group and at 12 and 22 for those of the second;these springs roll within these grooves. The springs are soldered tostuds c, and d, (i 1,2.....n) to which the terminals are attached, sothat the leaf of each spring remains tangential to the opposite walls ofthe rollers A and B (grooves 11, 21 and 12, 22) as shown in FIG. 6, thelatter being a partial sectioned view along the line 7 'y. The terminalsthemselves are in electrical contact with various elements which havenot been shown and, to this end, printed circuits are formed oncomponents A and B as stated hereinbefore.

Self-evidently, the invention is not limited to the embodimentsdescribed and illustrated here, purely by way of example. In particularthe relative sizes of the spring blades and their attachment on thepieces A and B, may be varied provided that there is not discontinuityinto the spring, which, at the attachment points, should be tangentialto the walls along which it is to roll. Last, the invention is notlimited to the electrical coupling of components which execute arelative linear or circular motion, but applies generally to any movement in which the potential energy of the elastic springs can bemaintained substantially constant, that is to say that the variation inthe radii of curvature of the faces guiding the spring strip remainssmall and that the radius of curvature r of the spring itself remainssubstantially constant, the shape of the walls on which the spring rollshaving to be matched to the movement in question; in all cases, theessential thing is that the coupling springs should roll on the guidesurfaces without any slip and that, during this movement, the electriclimit of the spring material should not be reached.

What is claimed is:

1. A rotary electrical coupler between two elements relatively rotatableabout an axis of rotation over a limited angular displacementcomprising, in combination:

a. said two elements each of which include a first element and a secondelement, said first element being positioned radially inwardly withrespect to its associated second element, said first and second elementshaving respective cylindrical walls concentric with respect to said axisof rotation, said walls having at least one pair of opposite walls whichare respectively integral with said first and second elements;

b. a plurality of conductive springs, each of said springs having a Ushape forming two ends, two linear portions and a curved intermediateportion, said two ends being respectively attached to said first andsecond elements, said two linear portions applying pressure respectivelyon the two opposite walls of a said pair of walls, said springs rollingwithout slip on said walls during said limited angular displacement andincluding one group of springs for each of said pair of walls, thesprings in each of said groups being staggered regularly and circularlyabout said axis of rotation; and

c. terminals for connecting said springs, each of said springs beingconnected by its two ends to two respective terminals for transmittingan electrical datum, said springs transmitting separate electrical databetween said elements.

2. A rotary electrical coupler between two elements relatively rotatableabout an axis of rotation over a limited angular displacementcomprising, in combination:

a. said two elements each of which include a first element and a secondelement, said first element being positioned radially inwardly withrespect to its. associated second element, said first and secondelements having respective cylindrical walls concentric with respect tosaid axis of rotation, said walls having at least two pairs of oppositewalls which are respectively integral with said first and secondelements;

b. a plurality of conductive springs, each of said springs having a Ushape forming two ends, two linear portions and a curved intermediateportions, said two ends being respectively attached to said first andsecond elements, said two linear portions applying pressure respectivelyon the two opposite walls of a said pair of walls, said springs rollingwithout slip on said walls during said limited angular displacement andincluding one group of springs for each of said pair of walls, thesprings in each of said groups being staggered regularly and circularlyabout said axis of rotation, said springs being distributed in at leasttwo groups offset parallel to said axis of rotation, said first andsecond elements having separate pairs of cylindrical concentric wallsrespectively associated with said groups of springs; and

c. terminals for connecting said springs, each of said springs beingconnected by its two ends to two respective terminals for transmittingan electrical datum, said springs transmitting separate electrical databetween said elements.

1. A rotary electrical coupler between two elements relatively rotatableabout an axis of rotation over a limited angular displacementcomprising, in combination: a. said two elements each of which include afirst element and a second element, said first element being positionedradially inwardly with respect to its associated second element, saidfirst and second elements having respective cylindrical walls concentricwith respect to said axis of rotation, said walls having at least onepair of opposite walls which are respectively integral with said firstand second elements; b. a plurality of conductive springs, each of saidsprings having a ''''U'''' shape forming two ends, two linear portionsand a curved intermediate portion, said two ends being respectivelyattached to said first and second eLements, said two linear portionsapplying pressure respectively on the two opposite walls of a said pairof walls, said springs rolling without slip on said walls during saidlimited angular displacement and including one group of springs for eachof said pair of walls, the springs in each of said groups beingstaggered regularly and circularly about said axis of rotation; and c.terminals for connecting said springs, each of said springs beingconnected by its two ends to two respective terminals for transmittingan electrical datum, said springs transmitting separate electrical databetween said elements.
 2. A rotary electrical coupler between twoelements relatively rotatable about an axis of rotation over a limitedangular displacement comprising, in combination: a. said two elementseach of which include a first element and a second element, said firstelement being positioned radially inwardly with respect to itsassociated second element, said first and second elements havingrespective cylindrical walls concentric with respect to said axis ofrotation, said walls having at least two pairs of opposite walls whichare respectively integral with said first and second elements; b. aplurality of conductive springs, each of said springs having a ''''U''''shape forming two ends, two linear portions and a curved intermediateportions, said two ends being respectively attached to said first andsecond elements, said two linear portions applying pressure respectivelyon the two opposite walls of a said pair of walls, said springs rollingwithout slip on said walls during said limited angular displacement andincluding one group of springs for each of said pair of walls, thesprings in each of said groups being staggered regularly and circularlyabout said axis of rotation, said springs being distributed in at leasttwo groups offset parallel to said axis of rotation, said first andsecond elements having separate pairs of cylindrical concentric wallsrespectively associated with said groups of springs; and c. terminalsfor connecting said springs, each of said springs being connected by itstwo ends to two respective terminals for transmitting an electricaldatum, said springs transmitting separate electrical data between saidelements.